Sail around the world

a colleague told me the other day that a relative of theirs has a desire to learn to sail and then sail around the world, so it got me thinking … in broad brushstrokes

How much should one spend on a boat? (im thinking just under 100k)

How long to train / learn before heading out on a (much-shorter) solo run? I reckon its x-years before trying to go across the Atlantic solo, let alone try the world.

If they join a good club, are there still jobs as paid deck hands to transport boats to & fro (to get experience of boat and ocean crossing)

What are the costs involved in long sailing (on top of actually living on a boat), eg mooring fees , using Panama canal, etc

Does one have to get visas to pass through other countries waters, even if you are not stopping?

….im just a bit jealous and entertaining this as a nice thought experiment.

Any tips / experience?